Device for removing gas from molten metals contained in a ladle

ABSTRACT

The invention relates to a device for removing gas from steel or other molten metal contained in a ladle. The ladle is housed in a multi-part vacuum container, and a reaction pipe connected to the vacuum container extends into the ladle and is immersed in molten metal when the latter is introduced into the ladle. The inner volume of the reaction pipe is greater than the increase in volume of the molten metal which occurs during degassing and metallurgical treatment of the molten metal.

llniteul States Patent [151 3,650,517 Messing Mar. 21, 1972 [54] DEVICE FOR REMOVING GAS FROM MULTEN METALS CONTAINED IN A LADLE memo Towed?!Ms zin zmhaofiiun52stdorf, Germany Standard-Messo Duisburg Gesellschaft fur Chemietechnik mit beschrankter Haftung 8: Co., Duisburg, Germany Filed: Aug. 19, 1970 Appl. No.: 65,032

Assignee:

Foreign Application Priority Data [56] References Cited UNITED STATES PATENTS 3,240,588 3/1966 Finkl ..266/34 V 3,320,053 5/1967 Lehman... 3,384,362 5/1968 Philbrick ..266/34 V Primary Examiner-Gerald A. Dost Attorney-Walter Becker [5 7] ABSTRACT 12 Claims, 1 Drawing Figure Patented March 21, 1972 3,650,517

INVENTOR.

DEVICE FOR REMOVING GAS FROM MOLTEN METALS CONTAINED IN A LADLE The invention relates to a device for removing gas from steel or other molten metals contained in a ladle.

In one known process for degassing molten metals a charged tapping ladle is placed in an evacuated container and an inert gas is introduced into the molten metal through the bottom of the ladle to remove gas from the metal by intense agitation. This causes the molten metal to boil and increase in volume. For this reason, a sufficiently large reaction space must be left in the ladle above the molten metal to prevent the slag or dross, or even the molten metal itself, from boiling over. The requirement of a sufficiently large reaction space when degassing in the ladle means that, for a given size of la dle, the charge must be relatively small. If, to increase output, larger charges have to be degassed, larger ladles must be used, to provide an adequate reaction space. The resulting weight of the ladle necessitates expensive alterations to the installation.

It is therefore an object of the present invention to provide a device in which the ladle can be filled with a normal charge without the molten metal boiling over.

This object and other objects and advantages of the invention will appear more clearly from the following specification in connection with the accompanying drawing which shows a longitudinal section of one form of device according to the invention.

The invention is characterized primarily in that an apparatus is provided for removing gas from steel or other molten metal which comprises a ladle for the molten metal, a vacuum container arranged to house said ladle, an upper portion of said container adapted to be movable and removable relative to a lower portion of said container, and a reaction pipe mounted within the upper portion of the container, the lower end portion of the pipe being arranged to extend into the molten metal within the ladle.

Referring now to the drawing in detail, the apparatus comprises a degassing container having a lower portion 1 and an upper portion 2. A flange 3 with an upwardly extending funnel-shaped guide portion 4 is provided on the lower portion 1. The upper portion 2 has a flange 5 by which it is supported on the lower portion 1, a sealing ring 6 being interposed between the flanges 3, 5. The lower portion 1 is also provided with a connection 7 for a pipe (not shown) leading to a vacuum pump. The upper portion 2 has an opening 8, equipped with a seal, to enable a nozzle 9 to be introduced, for feeding chemically reactive gases into the reaction space. A charging device 10, for solid alloying materials, is also provided in the upper portion 2.

A ladle 11 having a refractory lining 12, is placed in the degassing container and is filled with steel or other molten metal 13. Slag 14 floats on top of the molten metal 13. The bottom of the ladle 11 contains a plug of porous brick 15 with a gas feed pipe 16 for the introduction of an inert agitation gas, for example, argon into the molten metal 13.

Secured in the upper portion 2 of the degassing container by means of stays 17 is a reaction pipe 18 the lower end portion of which is immersed in the molten metal 13. The reaction pipe 18 is disposed below the charging device 10. At least the lower end portion of the reaction pipe 18 is encased in refractory material 19 and the volume of the reaction pipe 18 is greater than the increase in volume of the molten metal during the degassing and metallurgical treatment thereof.

In the embodiment illustrated, the lower end of the reaction pipe 18 is closed by a deflecting cap 20 when immersed in the molten metal 13, so that the slag 14 is directed into the annular-sectioned spaced defined between the ladle 11 and the reaction pipe 18. The advantage of the deflecting cap 20 is that the metal 13 can be given direct metallurgical treatment in the reaction space formed by the reaction pipe 18. I

The apparatus can, however, be used without the deflecting cap 20 when the presence of the slag 14 in the reaction space has no adverse effect on the metallurgical reactions.

To enable the ladle 11 to be centered precisely below the reaction pipe 18 that is to be introduced into it, the base of the degassing container is provided with guides 21 which receive feet 22 on the ladle 11.

Thus, in the device described, the ladles can be filled with a normal charge without the molten metal boiling over as a result of the increase in volume which occurs during degassing and metallurgical treatment.

The apparatus described is advantageous in that, without any increase in the size and weight of the ladle 11, a reaction space is formed above the molten metal, into which space the molten metal can rise when the agitation gas is admitted into the ladle and within which the molten metal can be treated metallurgically with reactive gases fed! through the nozzle.

The reaction pipe 18 can be cylindrical (as shown) or funnel shaped. Preferably the diameter of the lower end of the reaction pipe 18 is only a little smaller than the inner diameter of the ladle 11 at the same level, so that this portion of the annular-sectioned space defined between the reaction pipe 18 and the ladle 11 can be kept as small as possible.

In order to improve the effectiveness of the degassing and metallurgical treatment operations, the deflecting cap 20 should be made of a material which, when its enters the melt, does not react with the molten metal to form slag or reacts with the molten metal to form an alloy thereof.

In order that the lower end portion of the reaction pipe 18 is not damaged when the upper portion 2 is removed, the reaction pipe 18 should terminate a short distance above the lower end of the upper portion 2.

It is, of course, to be understood that the present invention is, by no means, limited to the specific showing in the drawing, but also comprises any modifications within the scope of the appended claims.

What I claim is:

l. A device for removing gaseous substances from molten metal, which includes: a multi-part vacuum container, the upper part of said vacuum container being movable and removable with respect to the lower part of said vacuum container, a ladle housed in said vacuum container, a reaction pipe supported by said upper part of said vacuum container, the bottom end of said reaction pipe extending into said ladle so as to be immersible in molten metal introduced into said Iadle, the inner volume of said reaction pipe being in excess of the increase in volume of the molten metal which occurs during degassing and metallurgical treatment of said molten metal.

2. A device according to claim 1, in which said reaction pipe is cylindrical.

3. A device according to claim 1, in which said reaction pipe is funnel-shaped.

4. A device according to claim 1, in which the outer diameter of the lower end of said reaction pipe is only slightly less than the inner diameter of the adjacent portion of said ladle.

5. A device according to claim 1, in which at least that part of said bottom end of said reaction pipe which extends into said molten metal is encased in refractory material.

6. A device according to claim 1, in which said bottom end of said reaction pipe is closed with a deflecting cap when said bottom end of said reaction pipe is immersed in said molten metal.

7. A device according to claim 6, in which said deflecting cap is made of a material which, when said deflecting cap becomes part of said molten metal, will not form slag.

8. A device according to claim 6, in which said deflecting cap is made of a material which, when said deflecting cap becomes part of said molten metal, will alloy with the molten metal.

9. A device according to claim 6, in which said deflecting cap is conical.

10. A device according to claim 1, in which said reaction pipe terminates short of the lower edge of said upper part of said vacuum container.

11. A device according to claim 1, in which inlet means are provided to permit the addition of alloying materials and reaction active gases into said reaction pipe from above and to permit the addition of agitating gas from below said reaction pipe.

12. A device according to claim 1, which includes centering means forming part of said lower part of said vacuum container for centering said upper part of said vacuum container and said ladle with respect to said lower part of said vacuum container. 5 

2. A device according to claim 1, in which said reaction pipe is cylindrical.
 3. A device according to claim 1, in which said reaction pipe is funnel-shaped.
 4. A device according to claim 1, in which the outer diameter of the Lower end of said reaction pipe is only slightly less than the inner diameter of the adjacent portion of said ladle.
 5. A device according to claim 1, in which at least that part of said bottom end of said reaction pipe which extends into said molten metal is encased in refractory material.
 6. A device according to claim 1, in which said bottom end of said reaction pipe is closed with a deflecting cap when said bottom end of said reaction pipe is immersed in said molten metal.
 7. A device according to claim 6, in which said deflecting cap is made of a material which, when said deflecting cap becomes part of said molten metal, will not form slag.
 8. A device according to claim 6, in which said deflecting cap is made of a material which, when said deflecting cap becomes part of said molten metal, will alloy with the molten metal.
 9. A device according to claim 6, in which said deflecting cap is conical.
 10. A device according to claim 1, in which said reaction pipe terminates short of the lower edge of said upper part of said vacuum container.
 11. A device according to claim 1, in which inlet means are provided to permit the addition of alloying materials and reaction active gases into said reaction pipe from above and to permit the addition of agitating gas from below said reaction pipe.
 12. A device according to claim 1, which includes centering means forming part of said lower part of said vacuum container for centering said upper part of said vacuum container and said ladle with respect to said lower part of said vacuum container. 